Measurements of leakage current produced during quiescence of an electronic device (i.e., “quiescent current” or “IDDQ”) may indicate a failure of one or more transistors of the device's logic circuitry. More particularly, when an IDDQ measurement falls outside of a range of normal operational values, it may be assumed that one or more transistors within the logic circuitry have failed. Accordingly, IDDQ measurements are often employed in manufacturing processes in order to identify and reject faulty devices prior to customer shipment.
A conventional method for measuring a device's IDDQ includes installing the device in a device carrier that is electrically interconnected with automated test equipment (ATE), and initiating an ATE IDDQ measurement test. In accordance with one IDDQ measurement method, a particular pin of the device is designated for the purpose of pinning out the internal voltage supply to the logic circuitry. With the internal voltage supply pinned out, an IDDQ measurement may be made by disabling the internal voltage supply and providing the supply voltage externally via the ATE. Using this method, IDDQ may be measured on the supply side of the logic circuitry. In accordance with another IDDQ measurement method, a particular pin of the device is designated for the purpose of pinning out the ground line to the logic circuitry. During testing, this pin is shorted to the main device ground externally, and IDDQ may thus be measured on the ground side of the logic circuitry.
Although such IDDQ measurement methods may be sufficient for testing some devices, they may be inadequate for testing others. For example, in die size limited and/or pin limited devices, it may be impractical to designate one or more pins for the specific purpose of performing IDDQ measurements. In addition or alternatively, some devices may include relatively small logic circuitry (e.g., logic circuitry with relatively few transistors), and an extremely small IDDQ (e.g., an IDDQ in a micro- or nano-amp range) may indicate a transistor failure. Conventional ATE used for IDDQ testing may not be capable of accurately measuring such small IDDQs. Inaccurate measurements may lead to faulty devices being released to customers.